Asolution of rubbing alcohol is 68.6 % (v/v) isopropanol in water. how many milliliters of isopropanol are in a 88.2 ml sample of the rubbing alcohol solution? express your answer to three significant figures.

From the information given, the total volume of  rubbing alcohol is 88.2 ml

68.6 % of this volume is isopropanol. 

We will assume 88.2 ml represents 100% volume, so the volume of water will be 31.4 %

The volume of isopropanol is

68.6/100 x 88.2 → 0.686 × 88.2 = 60.505 ml

The volume of isopropanol is 60.5 ml.

Volume of water will be 88.20 - 60.5 = 27.7 ml

(27.7 / 88.2 × 100 = 31.4% )

Adding 60.5 ml of isopropanol to 27.7 ml of water to make up 88.2 ml will give 68.6 % v/v isopropanol to water  solution.